1. Field
The present invention relates to a lithographic apparatus and a device manufacturing method. The present invention also relates to devices and methods for programming an array of individually controllable elements configured to modulate a beam of radiation.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs), and other devices involving fine structures. In a conventional apparatus, a patterning device, which can be referred to as a mask or a reticle, can be used to generate a circuit pattern corresponding to an individual layer of a flat panel display or other device. This pattern can be transferred onto a target portion (e.g., comprising part of one or several dies) on a substrate (e.g., a glass plate). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (e.g., resist) provided on the substrate.
Many scanners employ a movable chuck (or object table) for supporting the substrate which passes through the patterned beam. In machines of this type, an accurate position control of the substrate with respect to the patterned beam is desired. In general, a positioning device comprising linear electromagnetic actuators or motors are applied to accurately position the movable chuck that supports the substrate. These actuators or motors are supplied from a single phase or a multiphase power supply and controlled by a position controller. In order to accurately position the substrate, a comparatively high bandwidth of the position controlled loop can be required.
In a lithographic apparatus for manufacturing FPD substrates, the chuck for moving the substrate is generally very large (e.g., FPD substrates are typically up to 1-2 m along each side) and heavy. The servo bandwidth can be limited in this respect by the internal dynamics of the chuck in case these dynamics are excited by the forces of the positioning device.
Because a lithographic apparatus is usually applied in a clean room environment, a small footprint of a lithographic apparatus is desired because this allows the customer to apply the available space in the clean environment as effective as possible. Therefore, it is desired to have a compact positioning device in order not to increase the overall size of the apparatus. This applies in particular to a lithographic apparatus for manufacturing FPD substrates because of the large size of the FPD substrates.
In a lithographic apparatus for manufacturing FPD substrates, the substrate can be irradiated by a beam, while synchronously scanning the substrate relative to the beam. The positioning device accurately positions the substrate relative to the beam, at least in a plane perpendicular to the direction of the beam. In general, the required displacement (provided by the positioning device) will be substantial in the scanning direction, while only minor displacements are required in a direction perpendicular to the scanning direction and perpendicular to the direction of the beam because in most cases. The projection system can extend over the entire width of the substrate.
Conventional positioning devices that are used to displace objects or object tables over large distances in one direction (e.g., the scanning direction) and over comparatively small distances in a direction perpendicular to this direction (e.g., positioning devices for displacing a reticle stage) are often not optimized with respect to the dynamic behavior due to the internal dynamics of the chuck.
Therefore, it is an object of the present invention to provide an improved positioning device wherein the effects of the internal dynamics are mitigated.